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Surface Ocean and Lower Atmosphere Study—Air-Sea interactions and their climatic and environmental impacts
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Aerosol hygroscopicity in East Asian from continental to marine environments
Wednesday 9th @ 1110-1130, Conference Room 7
Yu Wang* , State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University
Now at: Centre for Atmospheric the Science, School of Earth and Environmental Sciences, The University of Manchester
Zhijun Wu, State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University
Shan Huang, Institute for Environmental and Climate Research, Jinan University
Alfred Wiedensohler, Leibniz Institute for Tropospheric Research
Min Hu, State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University
Presenter Email: yu.wang@manchester.ac.uk |
| The water uptake of atmospheric aerosols plays an important role in aerosol chemistry, visibility degradation, cloud formation, and human health. Particle hygroscopicity measurement has been deployed in various environments worldwide, including urban, rural, marine, forest, remote areas, mainly in Europe and USA. In the past 20 years, the particle hygroscopicity measurement in Eastern Asia was largely enriched. This study summarized the outcomes of the hygroscopicity of the sub-micrometre particles measured by H-TDMA (Hygroscopicity-Tandem Differential Mobility Analyzer) from continental to marine environments in Eastern Asia. To avoid the influence of kelvin effect on the growth factor, the single parameter (k) was used to characterize particle hygroscopicity. k=0 means hydrophobic (e.g. black carbon), while the k of atmospheric-relevant inorganics such as (NH4)2SO4 and NaCl are 0.50 and 1.27 respectively. The mean k of urban aerosols were roughly 0.10~0.33, while, the mean k for rural aerosols was slightly higher with 0.15~0.40. The mean k at a mountain site (Huangshan, China), a forest site (Wakayama, Japan), a near-coastal site (Hongkong, China) and a marine site (Cape Hedo, Okinawa, Japan) were 0.20~0.30, 0.20~0.40, 0.20~0.40 and 0.45-0.55 respectively. The mean k of aerosols in North Pacific Ocean was 0.4~0.6 when the air mass sourced from marine/volcano-Japan, while the mean k ranged 0.2 to 0.4 when the air mass was influenced by polluted continental areas. Typically, urban and rural aerosols showed 2~3 hygroscopic modes (nearly-hydrophobic, less-hygroscopic, more-hygroscopic mode), indicating an external mixing state of atmospheric particles. However, high frequency of a single mode (hydrophilic mode) was observed in the mountain site, indicating internal mixing state of aerosols. Besides, when the air mass was from marine sources, sea salt/sulfuric acid mode was observed in the marine site and ship measurement. Based on particle hygroscopicity and chemical composition measurements in various environments, a linear relationship between particle hygroscopicity (k) and the organic mass fraction (Forg) was established. Interestingly, measurements from all the continental areas (including polluted & clean urban, rural areas, mountain site) and the marine environment influenced by continental air mass shared the same parameterization equation: k = (-0.492±0.007) * Forg + (0.505±0.004). However, the marine environment influenced by marine air mass showed a different parameterization equation: k = (-2.120±0.023) * Forg + (0.987±0.006). These findings are essential to improve our understanding of particle hygroscopicity in Eastern Asia and extend the mapping of hygroscopic measurements globally. |
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